Least Tern

Sterna antillarum

The Least Tern is the
smallest of the North American terns. They breed in two distinct habitats,
the sandy beaches of the Atlantic and the Californian Pacific coast, and on
sandbars on large river systems in the interior of the country. Both the
coastal and inland populations are endangered. In South Dakota, they breed
along sandbars of the Missouri River system, but are endangered by the unnatural
fluctuations in river levels caused by management of water releases from
Missouri River system dams. Along the coastlines, they are endangered by
human disturbance on their nesting beaches. There is some hope that
coastal populations, at least, have adapted to a human presence somewhat by
including gravel roofs as areas to nest.

Habitat: In the interior of the country,
breeds on large river systems with large exposed sandbars. Along the
coastline, breeds on sandy beaches adjacent to shallow water. During the
winter, found along tropical coastlines and sometimes far out to sea.

Diet: Primarily feeds on small fish,
crustaceans, and insects. Will also eat small mollusks and marine worms if
available.

Behavior: Forages while in flight, hovering over
the water and plunging down just below the surface to capture fish and other
prey items when spotted. They are also capable of catching flying
insects while in flight.

Nesting: May through July

Migration: In summer, can be found locally inland on
large river systems, along the Atlantic coast, and locally along California's
Pacific coast. Both coastal and interior populations migrate well to the
south in winter, inhabiting tropical waters down through Brazil.

Conservation Status: Endangered in many parts of
its range. In the interior of the continent, unnatural water
fluctuations due to regulation of rivers with dams often results in
unsuccessful nesting. On the coastlines, human disturbance on beach
nest sites often causes unsuccessful nesting.